Confined Rhodium catalyst by self-assembly for asymmetric hydroformylation of unfunctionalized, internal alkenes.

Transcription

1 Confined Rhodium catalyst by self-assembly for asymmetric hydroformylation of unfunctionalized, internal alkenes. Tendai Gadzikwa, Rosalba Bellini, Henk L. Dekker and Joost. H. Reek* van t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The etherlands. Materials All chemicals were used as received from commercial sources. Rh(acac)(C) 2 (Strem Chemicals Inc.), acetone and methylenechloride (Biosolve B.V.). Toluene was freshly distilled under argon over sodium and kept under Argon. Instrumentation Elemental analysis was performed by Microanalytisches Laboratorium Kolbe (Mülheim an der Ruhr, Germany) after drying under vacuum at room temperature. 1 H MR and 31 P MR spectra were recorded on a Varian IVA 500 MR spectrometer (500 MHz for 1 H, 125 MHz for 13 C, and 202 MHz for 31 P). 1 H MR chemical shifts were reported in ppm against residual solvent resonance as the internal standard (δ(acetone) = 2.05 ppm). Gas Chromatography (GC) analyses were performed on a Shimadzu GCT17A instrument (split/splitless injector, J&W Scientific, DBT1 J&W 30 m column, film thickness 3.0 µm, carrier gas 70kPa He, FID Detector). Chiral GC separations were conducted on an Interscience HR GC instrument with a Supelco βtdex 225 capillary column. Electrospray ionization (positive mode) was done with a Q-Tof1 mass spectrometer of Micromass (Waters). Circular dichroism (CD) spectra were recorded on a LIS DSM-1000 CD-Spectrometer. Preparation and Characterization of Supramolecular Structures Compounds 2 1 and 3 2 were prepared via literature procedures. 1. Compound 1. To an Erlenmeyer flask charged with compound 2 (83 mg, 0.16 mmol) and 3 (180 mg, 0.16 mmol), acetone was added until all solids were dissolved. The flask was allowed to sit overnight, at which point red powder/crystals had precipitated out. The solid was collected by filtration, rinsed with acetone, and dried under reduced pressure (224mg, 68 mmol, 85% yield). 31 P MR (500 MHz, acetone-d 6 ): δ 144 (s). 1 H MR (500 MHz, acetone-d 6 ): δ 9.21 (8H, 3 ArH), 9.08 (2H, 2 ArH), 8.92 (2H, 2 ArH), 8.56 [6H (4H, 3 ArH)+(2H, 2 ArH)], 8.44 (2H, 2 ArH), 8.27 (2H, 2 ArH), 7.92 (2H, 2 ArH), 7.70 (4H, 2 ArH), 7.45 [10H (8H, 3 ArH)+(2H, 2 ArH)], 7.05 (8H, 3 ArH), 7.02 (2H, 2 ArH). EA: Calculated for evacuated 1 (C 196 H P 2 Zn 4 ): (%) C, 71.26; H, 7.20;, Found: C, 69.44; H, 7.20;, Figure S1. 1 H MR spectrum of 1. S1

2 Figure S2. 31 P MR spectrum of 1. Titration of 3 against 2 monitored by CD spectroscopy CD (millidegrees) Δ CD (millidegrees) Wavelength (nm) Equivalents 3 Figure S3. CD spectral titration curves for the assembly of 1 (left) ΔmD nm (right). Fixed concentration of 2 (2.46 x 10-5 M in acetone), 1.00mm path length quartz cuvette. S2

3 Diffusion MR data for 1 The diffusion MR experiments were carried out using the diffusion bipolar pulse pair stimulated echo (DBPPSTE) method. Measurement of T 1 was carried out before each experiment. Δ = 100 ms and δ = 2 ms, and and T = K. Samples were 8.3mM in d 6 -acetone ln(i/i0) G 2 (T 2 m - 2 ) Figure S4. A stacked plot of the aromatic area of the1h MR spectrum of 1 as a function of applied gradient strength (left). A linear fit of the diffusion (right). I = G I γ δ ( Δ δ ) 3 0 ln r KbT = 6πηD H = [ D] = T m T m T m T m = = m s D = γ δ m s kg = 1.01 x 10-9 m ms kg = 2 2 ( Δ δ ) γ δ ( Δ δ ) T s 2. Compound 1-Rh. To a Schlenk flask charged with compound 1 (100 mg, 30 µmol) and Rh(acac)(C) 2 (7.8mg, 30 µmol), and equipped with a magnetic stir-bar, distilled toluene (5 ml) was added under a nitrogen atmosphere. The flask was allowed to stir overnight at 80 C, after which an unlocked 31 P MR spectrum of the crude reaction reveals the absence of the singlet corresponding to compound 1, and the presence of a new doublet. The reaction is then brought to room temperature, and the solvent removed under reduced pressure. The resulting solid was then characterized without further purification. 31 P MR (500 MHz, acetone-d 6 ): δ (d, J Rh-P = 292 Hz). ESI-MS: Calculated (C 201 H P 2 Rh 1 Zn 4 ): m/z (%) (100.0%), (96.4%), (90.2%). Found: , , Figure S5. 31 P MR spectrum of 1-Rh. S3

4 ESI-TF MS spectra for 1-Rh An offline spray was made by filling a glass standard coated Econo10 tip (ew bjective) with a solution of the constructed supramolecular complexes in Toluene. Ions visible within the m/z window of were selected from the TofMS spectrum. A collision-induced dissociation was performed with the selected ions. Masslynx software was used for the processing of the acquired data and modeling of the isotope pattern. Figure S6. ESI-TF MS of 1-Rh. Figure S7. MS-MS of ESI-TF MS peak at 1752 (Figure S6). S4

5 [C 201 H P 2 RhZn 4 ] 2+ [C 98 H PZn 2 ] + Zn Zn Zn Zn 2+ P P Rh I I Zn Zn P H [C 69 H P 2 Rh] + [C 66 H Zn 2 ] 2+ P H P Rh Zn Zn H Figure S8. Magnification of MS-MS peaks. Black: model calculated in Masslynx. Green: Experimental. Computational details The structure was generated in Spartan 08, using the previously obtained X-ray structure of 2 as a starting point. 2 After generating the structure 1-CRhH-octene, the assembly was first optimized using constraints on the salphen building blocks (2), and in the final PM3 optimization no constraints were applied.. S5

6 Catalysis Procedures and Results: A stainless steel autoclave (150 ml) was fitted with an insert capable of holding multiple GC vials (1.5 ml) to run reactions in parallel. Each vial, equipped with a Teflon stir bar, was charged with the appropriate ligand (9 µmol ligand 2, 5 µmol all bidentate ligands), Rh(acac)(C) 2 (1 µmol), the substrate (200 µmol), decane (20 µl), and then distilled toluene (1 ml) was added, all under ambient conditions. Each vial was then capped with a septum cap, which was then punctured with a needle (25G x 5 / 8 "), which was left piercing through the cap throughout the catalysis. The autoclave was sealed and purged (3 x 10 bar) with syngas (H 2 /C = 1:1), then pressurized to 20 bar, and the vials left stirring for 84 h. The autoclave was then vented to 1 atm and each reaction quenched with a drop of tri-nbutylphosphite. Aliquots were diluted with CH 2 Cl 2 for GC analysis. Table S1. Evaluation of the substrate scope of ligand 2. a Entry Substrate % conv b % inner er c 1 trans-2-nonene :38 2 cis-2-nonene :48 3 trans-2-octene :39 4 cis-2-octene :52 5 trans-2-heptene :41 6 cis-2-heptene :53 7 trans-3-hexene 10 na 45:55 8 cis-3-hexene 23 na 44: octene 8 32 nd 10 styrene 8 >99 47:53 d a All reactions were performed at 25 C in toluene with 20 bar 1:1 C/H 2, 0.5 mol % Rh(acac)(C) 2, 2.5 mol % 1 and 84 h reaction time. b GC conversions reported. c The er values were determined by chiral GC only for the innermost aldehyde. d S:R. Chart S1. ptimization of ligand 1 to Rh ratio. S6

7 Table S2. High temperature (70 C ) catalysis results for 1.. Entry Ligand Substrate % conv % isomerization products % b er b (R:S) 1 2 trans-2-octene : cis-2-octene : trans-2-octene : cis-2-octene :12 Gas chromatography details Gas Chromatography (GC) analyses were performed on a Shimadzu GCT17A instrument (split/splitless injector, J&W Scientific, DBT1 J&W 30 m column, film thickness 3.0 µm, carrier gas 70kPa He, FID Detector). Initial temp: 70 C, hold 1 min. Ramp 1: 7 C/min to 120 C. Ramp 2: 13 C/min to 250 C, hold 5 min. Table S3. Response factors of alkenes with decane internal standard. Area Area substrate decane = f mol mol substrate decane Substrate f trans-2-nonene 0,9536 cis-2-nonene 0,8072 trans-2-octene 0,7994 cis-2-octene 0,7052 trans-2-heptene 0,6618 cis-2-heptene 0,6257 trans-3-hexene 0,4743 cis-3-hexene 0, octene 0,7461 styrene 0,758 Chiral GC separations were conducted on an Interscience HR GC instrument with a Supelco βtdex 225 capillary column. Initial temp: 80 C. Ramp 1: 1 C/min to 95 C. Ramp 2: 40 C/min to 200 C, hold 2 min. GC traces in Appendix. (1) Bellini, R.; Chikkali, S. H.; Berthon-Gelloz, G.; Reek, J.. H. Angew. Chem. Int. Ed. 2011, 50, (2) Kleij, A. W.; Kuil, M.; Tooke, D. M.; Lutz, M.; Spek, A. L.; Reek, J.. H. Chem. Eur. J. 2005, 11, S7

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